Butene-1 polymers of the type which are modified according to this invention are described Ser. No. 369,388, filed Apr. 19, 1982, a continuation-in-part of Ser. No. 331,106, filed Dec. 16, 1981, now abandoned. They will be referred to herein as stereoregular elastomeric polybutylene or simply elastomeric polybutylene. These polymers differ significantly from conventional isotactic polymers of 1-butene. The latter are well known materials which, in their commercially available form, typically have a crystallinity in the range from 50-60%, determined by X-ray diffraction. The crystallinity of the elastomeric polybutylenes is typically in the range from 25 to 40%.
Heterogeneous nucleation via the addition of a foreign material or nucleating agent is well known. See, for example, Chatterjee et al, J. Polym. Sci.; Polym. Phys. Ed., Vol. 13, 2369-83 and 2385-90 (1975). As demonstrated therein, heterogeneous nucleation is highly selective and there is no evidence of a universally strong nucleating agent for all polymers. In other words, an effective nucleating agent for one polymer may be ineffective for even a closely related polymer; similarly, even a compound closely related to an effective nucleating agent for one polymer may be ineffective for that same polymer. Nucleation and specific nucleating agents are discussed in Binsbergen, J. Polym. Sci.; Polym. Symposium, No. 59, 11-29 (1977).
The use of a nucleating agent to accelerate the crystallization of polymers allows for faster processing and results in a more uniform microstructure because of the reduced size of the spherulites which form upon melt crystallization. The products also generally demonstrate improved physical and mechanical properties. See, for example, Rubin, Injection Molding Theory and Practice, pp. 192ff(1972). In general, a desirable nucleating agent is effective at low levels of addition, both for reasons of economy and the avoidance of undue foreign structural heterogeneity which may otherwise adversely affect the properties of the polymer.
In a study of nucleation of conventional poly(1-butene) I have found a variety of compounds that are effective crystal nucleants for that polymer. Some of these are disclosed in my U.S. Pat. Nos. 4,321,334--certain types of graphite; 4,320,209--certain amides and imides; 4,322,503--certain amides of fatty acids; and in pending application Ser. No. 366,807, filed 4-8-82, which is a continuation-in-part-of Ser. No. 218,865, filed 12-22-80, now abandoned--certain anthraquinones.